1. Field
The following description relates to a power amplifier.
2. Description of Related Art
In accordance with a rapid increase in demand for a high data rate in a wireless transmitting and receiving system, a multi-carrier scheme or a complicated digital modulation scheme has been adopted to provide this feature. Therefore, a power amplifier included in a transmitting and receiving module that performs wideband code division multiple access (WCDMA) or long term evolution (LTE) communications has been designed to have high linearity.
For example, in an example in which modulation schemes such as quadrature amplitude modulation (QAM) in a higher modulation scheme than a binary phase shift keying (BPSK) modulation scheme are used, linearity of the power amplifier further deteriorates.
However, since there is generally a trade-off between the linearity of the power amplifier and power efficiency of the power amplifier, constructing a power amplifier to have high linearity may have a negative influence on the power efficiency. For example, in order to improve the linearity of the power amplifier, a bias voltage of a gate terminal of a field effect transistor (FET) included in the power amplifier may be adjusted, which may have a large influence on the power efficiency of the power amplifier. In addition, a control of the linearity by the bias voltage of the gate terminal is sensitive to a change in process-voltage-temperature (PVT) issues.